1290 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1956 



Table I — Summary of M1789 Design 



I. Helix Dimensions 

 Mean Diameter 

 Inside Diameter 

 Wire Diameter 

 Turns per Inch 

 Pitch 



Wire Diameter/Pitch 

 Active Length 

 II. Voltages and Currents 



Electrode 



III. 



IV, 



V. 



90 mils 



80 mils 



10 mils 



34 



29.4 mils 



0.34 



5^ inches 



Voltage 

 (volts) 



Cathode 



Beam Forming Electrode 



Accelerator 2600 



Helix 2400 



Collector 1200 

 Heater Power 

 TWT Parameters at Midband (6175 mc) 



6 watts 



Current 

 (ma) 



40 







< 0.1 



<0.4 



>39.5 



ka 



C 



QC 



1.58 

 0.148 

 0.058 

 0.29 

 30 



As defined by Tien' 



N (number of X's on helix) 



Dielectric Loading factor 0.79 



Impedance Reduction factor 0.4 



Electron Gun 



Gun type — Converging Pierce Gun 



Cathode type — Spraj'ed oxide 



Cathode Current Density 213 ma/cm^ (for/x = 40 ma) 



Cathode diameter — 192 mils 



Convergence half angle 12° 40'_ 



Cathode radius of curvature (r^) 438 mils 

 Anode radius of curvature (/•„) 190 mils 

 It^c/n, 2.3 



Pervernce 0.3 X 10~^ amps/volts^'z 



VVa/Tk = 1.61 for Tk = 720°C 

 At the beam minimum in absence of magnetic field: 

 rmin (from Pierce^") 



from Danielson, Rosenfeld & Saloom^ 



r9i 



Tt/a- 



a 



Brillouin flux density for 80 mil helix ID 

 Actual focusing flux density required 

 Beam transmission from cathode to collector at 5 watts 

 output 



99% 



For an explanation of symbols see page 1345. 



